Display graphics options VSYNC labels as "every frame, every 2. frame, every 3. frame" - this is how 60, 30, 20 currently work

Indeed. That is technically called the “V-Sync Present Interval” in DirectX (aka Swap Interval), so that’s how it should be labeled and described in the interface.

V-Sync Present Interval = 1 or 2 or 3 (FPS limit is entirely dependent on display refresh rate)

And that’s precisely how some other games describe it properly.